AIDJEX Bulletin #40 - Polar Science Center - University of Washington

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Az i mu t h s When both receivers at a camp recorded a trunmttd fix from the same satellite, the azimuth and distance separating the two antennas were computed. There were about a dozen such NavSat azimuth determinations each day for each camp and, weather permitting, one celestial azimuth measurement. The celestial azimuths were taken with a theodolite and were accurate to 20.1'. The NavSat azimuths had 68th percentiles of about +2', and biases from 0' to 3'. Figure 9 is an example of NavSat and celestial measurements of floe rotation. 250 ' + .?k +, +:-* .-r ........ - ..-. + .- -*: ,:: . ........... Y '9 u r... P.. - .". * 9 ++. . -. *.- .+: > cc + ......... . . . 0 '* -a w . " +. .... . -.. m 0 * - c. ... + .. + ..&*++ .. ..7 ' + ................ 2 .t +*. .-. .. - ++ .... - - . .".. - -E ........... I- '-1 .. 2- ...... * a ..... * -I . ?+:. -! .) -a c( . .- b v3 .... ...... . Y -8 ... ... .. - . Fig. 9. Floe rotation as measured by NavSat and celestial methods for camp 3 (Snow Bird) during July 1975. Significant bias 1s- present in the NavSat measurements. 95
VELOCITY ERROES As mentioned earlier, the February data were selected for detailed study because the ice was nearly stationary then. Clearly, such data do not include fix errors due to ice velocity itself. In the general situation when the ice is moving there is an additional source of error. The measurement equation which we used, relating the observer’s position to the corrected Doppler counts, did not take into account velocity of the observer. In principle the velocity can easily be included in the measurement equation--in fact, it is standard practice for shipboard applications-- but we decided to ignore the velocity effect for several reasons. Ice velocities are typically small and highly correlated between stations only 100 km apart. Thus the velocity errors in translocation will be small. Also, we were not confident of a technique to estimate the ice velocity based on the previous few fixes. The effect of velocity errors could have been reduced by a suitable algorithm to, estimate the ice velocity and use it in the fix solution. The histogram of ice velocity (Fig. 10) shows that the velocity error could occasionally exceed 20 cm sec-’ , with which, using the above guideline, is associated a fix error of at least 100 m. The difference in velocity between two stations will affect our translocation results. The velocity difference was occasionally as large as 10 cm sec-’ (FiF. I), causing occasional translocation errors of more than 50 m. Thus, we can see that at times of extreme ice motion, the effect of velocity errors is somewhat larger than the other sources of error in stand-alone and translocation position measurements. The errors in position due to velocity errors are roughly proportional to the ice velocity itself (50 m per 10 cm sec-l). Likewise, the distance traveled by the ice in a given tine (12 hours, say) is also proportional to the velocity. Thus, the ratio of the measurement error to the actual motion is independent of the ice velocity, and is about 0.02. While position errors due to the ice velocity are not negligible, they degrade our estimates of ice motion over periods of 12 hours or so by only approximately 2%. 96
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DATA BUOYS AIDJEX BULLETIN No. 40 J
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NOTE TO FRIENDS, AND BYSTANDERS . .
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SUMMARY OF TECHNICAL DEVELOPMENTS I
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milestones, kept the vendor working
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The scene during deployment of HF-N
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The initial AIDJEX scientific plan
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poizr-orbiting satellite, which is
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t@ the spacecraft during each orbit
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BUOY NAHE COMMUN. COMMANDS FIXES TA
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L( 0 I 2 3 4 3 Radial error, kilome
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The buoy will be subjected to tempe
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nics occupy about 12 feet of the 17
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Ill -- - KEY AIUJEX WIN WW AEBa 0 4
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event that a melt pond should form
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chute supplied by Paranetics Inc. i
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6'" IqORGANIC LITHIUM BP.TTEI?Y IMP
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OM (AD RAMS) UREMEN~ \ AIRDROP N m
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provides a grid from which geostrop
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words; a four-bit air temperature w
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PERFORMANCE OF MET/OCEAN BUOYS IN A
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Sensor samples were taken every thr
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strengths are known, were used with
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the ice (causing reduced shear). An
Page 48 and 49: (McPhee, Mangum, and Martin) , TABL
Page 50 and 51: 70°N 75'N n 3 P 17OOW (D Y 170°W
Page 52 and 53: 12OOW * U Station 25. Xeasurements
Page 54 and 55: (McPhee , Mangum, and Martin) 2701
Page 56 and 57: (McPhee, Mangum, and Martin) a 0 a
Page 58 and 59: "i BUOY 4 I 43 360- 309- 257 206 15
Page 60 and 61: a30gl 251 I 60 511 r 43 BUOY 4 I
Page 62 and 63: n 4, (McPhee, Mangum, and Martin) 8
Page 64 and 65: (McPhee, Mangum, and Martin) 33 W c
Page 66 and 67: . '-,..I.. . B A R R O W W I N D S
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Page 70 and 71: I 25 23 t h--:!li[ NCI PiHCEl4l 22
Page 72 and 73: .5 .4 .3 0 A R 2 R 0 W J - 0 B U -
Page 74 and 75: 9 1.5 1.0 c 8 w .5 R 930 $ 565 1000
Page 76 and 77: Clock corrections were applied rout
Page 78 and 79: Q) u o z z i 4- 4- Z + + z f n 9 Ef
Page 80 and 81: TABLE 1 DIFFERENCES IN DAILY TEMPER
Page 82 and 83: Laboratory calibration of the ADRAM
Page 84 and 85: 3.20- - 1 t W o? 2 3.051 ...:-.;..
Page 86 and 87: POSITION MEASUREMENTS OF AIDJEX MAN
Page 88 and 89: some redundancy. Four points were u
Page 90 and 91: 75.5 75.: - E75.1 LLI % y75.c - 1 1
Page 92 and 93: The translocation principle removes
Page 94 and 95: POSITION ACCURACY To evaluate the q
Page 96 and 97: TABLE 1 STAND-ALONE ACCURACY 68th P
Page 100 and 101: DATA PROCESSING Following the field
Page 102 and 103: model ice motion in the statistical
Page 104 and 105: FREC 1 INCY / DOPPLER / FREQUENCY /
Page 106 and 107: 35 30 25 v) > 0 2 20 LL 0 r= E m 15
Page 108 and 109: An example of a large-scale buoy ar
Page 110 and 111: observations are needed in remote a
Page 112 and 113: useful for determining how various
Page 114 and 115: as well as velocity fields, we must
Page 116 and 117: Since small changes in the yield su
Page 118 and 119: The transformation of the system of
Page 120 and 121: e able to judge how well such a mod
Page 122 and 123: then the flow rule becomes Q = +A -
Page 124 and 125: [-B' -F Finally, we eliminate Carte
Page 126 and 127: differential equation. 2. Discontin
Page 128 and 129: Substituting (36) and (37) into (34
Page 130 and 131: arbitrarily assign the values of 1
Page 132 and 133: The special case when advection can
Page 134 and 135: TABLE 1 STRETCHING, STRESS, ASP CHA
Page 136 and 137: ate of deformation, we have normali
Page 138 and 139: CHARACTERISTIC EQUATIONS The ordina
Page 140 and 141: One way to circumvent the problems
Page 142 and 143: The equations governing solutions a
Page 144 and 145: It is readily seen that when body f
Page 146 and 147: which may be substituted into equat
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a the stress derivative dCldS remai
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Although we have not studied in thi
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Courant, R., and D. Hilbert. 1962.
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A RESEARCH PLAN TO TEST THE AIDJEX
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the barges managed to reach their d
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APPROACH A baseline simulation 0-f
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SENSITIVITY OF ICE RESPONSE TO DIFF
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Since free drift of ice is computed
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and what is observed becomes less i
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stresses appear to be relatively un
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ehavior is directly related to accu
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TABLE 1 COMPARISON OF ESTIMATED ERR
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a) Base line b) 24-hour prediction
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\ / a) Base line b) 24- hour predi
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a) Base line b) 24- hour predi ct i
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\ / a) Base line b) 24-hour predict
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.. a) Base line b) 24- hour predict
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J2 a) Base line b) 24-hour predicti
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) 24-hour prediction c) 36-hour pre
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8 Figure 17. AIDJEX surface pressur
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APPENDIX 1 AIDJEX DATA FILES 1. Pos
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9A. Surface-1 eve1 ai r pressure (d
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19. Surface pressure (Val i dated)
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APPENDIX 2 AIDJEX DATA TRANSFERRED
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I -7-71327GEO A Cards (continued) 7
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B Cards (continued) 201
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AIDJEX Bulletin #40 - Polar Science Center - University of Washington

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